Apparatus for producing ground and polished glass strip



Oct. 17, 1939.. F. B WALDRON El AL I APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP Filed March 4, 1938 3 Sheets-Sheet 1 Oct. 17, 1939. WALDRON AL 2,176,480

APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP 3 Sheets-Sheet 2 Filed March 4, 1938 Oct. 17, 1939. 2,176,480

APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP F. B. WALDRON ET AL Filed March 4, 1938 3 Sheets-Sheet 3 H628. IQ;

Patented Get. 17, 1939 NITED STATES PATENT OFFICE APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP ited Liability Acts Application March 4, 1938, Serial No. 193,907 In Great Britain March 10, 1937 2 Claims.

ground and polished strip of glass from the molten glass in a single operation and has for its object a method and apparatus for keeping the strip central in the grinding and polishing apparatus.

The invention is applicable to that type of apparatus in which a continuous strip of glass is rolled and annealed and then ground and polished simultaneously on both sides and is not supported in the grinding and polishing apparatus except by the grinding and polishing tools.

Such apparatus comprises a supply of molten glass, a strip-forming apparatus, a leer and a grinding apparatus, generally followed by a polishing apparatus.

The strip is liable to deviate from a central position in its travel to the grinding apparatus and when it so deviates either the strip must be forced back to its central position or the grinding and polishing tools must be moved to occupy a central position relative to the strip. There is, however, difliculty in determining the position of the strip, because it varies in width and has edges which are not usually rectilinear. The position of the strip cannot therefore be determined by the position ofits edge.

According to the invention, means are provided for indicating the position of the centre line of the strip at a point in or near the grinding apparatus, when the strip is of variable width, and means dependent on the indications are provided for bringing approximately together the centre line of the strip and the centres of the tools. The indicating means may be a groove formed in the strip near the forming apparatus where the strip is plastic or it maybe one or two bands of opaque paint or the like laid on the strip where thisv still occupies a predetermined position, or it may be two rollers or the like positioned by the two edges of the strip respectively, linked to a pivoted bar. The means for bringing together the centre line of the strip and the centres of the tools may be means adapted to press the strip edgewise, operated by the indicating means.

In the accompanying drawings:

Figure 1 is a diagrammatic side view of an apparatus for producing a ground and polished strip of glass, the part A in the lower part of the figure being a continuation of the part A in the upper part;

Figure 2 is a section Figure 1;

Figure 3 is a front view of a device for operthrough the line 3-3 of This invention relates to the production of a ating a pressing device, with a portion of the strip in section;

Figure 4 is a plan view of a pressing device;

Figure 5 is a diagrammatic view of a light sensitive device for operating a pressing device;

Figure 6 is a plan view of a device for indicating the positionof the centre line of the strip and operating a pressing device;

Figure '7 is a diagrammatic part front view of the rollers of the rolling apparatus showing an alternative form of strip grooving device;

Figure 8 is a cross section of a grinding apparatus with transversely moving tools, and

Figure 9 is a diagrammatic view of a relay switch device.

Referring to Figure 1, the glass l in the tank 2 flows to the rolling apparatus 3, which forms the strip 4. The strip is supported on a roller bed 5 and passes into the leer 6., and from thence passes between the disc grinding tools I and the disc polishingtools 8. -The strip 4 is driven between the tools by pairs of rollers '9. The strip is formed by the apparatus 3 in a position predetermined with reference to the apparatus, but is of variable width, the width being dependent on thirds of the way down, is suflicient to deflect the position of the strip in the grinding and polishing apparatus, at a point some hundreds of feet distant, by several inches, and bring it into' incorrect position relatively to the tools.

An extremely small lateral curvature at a point in the leer, say, half or two- Referring to Figure.2, a roller 10 is employed tov make a V-groove H in the strip '4, while it is still plastic. The roller 50 may be in the position shown in Figure 1, above one of the rollers 5- of the roller bed. At this point, the strip is in the position determined by the forming apparatus 3, and therefore the V-groove made at a fixed distance from the centre line of the strip, serves as an indicator of the centre line. Alternatively, the V-groove may be made by a V- ridge Illa formed on the upper roller 3 of the rolling apparatus as shown in Figure 'I.

Figure 3 shows the device-located at any suitable point in the grinding or polishing apparatus, or immediately before the grinding apparatus, for indicating the position of the centre line of the strip at this point.- A roller E2, on the end of an arm l3 of a lever pivoted at l4 to an arm l5 which is pivoted to a fixed support l6, engages the groove in the strip 4. The other arm I! of the lever engages at l8 the operating arm IQ of a valve box 20. A spring 2| maintains the roller 2 in engagement with the groove I I. Since the V-groove indicates the position of the centre line of the strip 4, the arm I9 is moved to the right or left of its central'position as the centre line of the strip moves to the right or left of the line through the centres of the tools. Any movement of the arm I9 is used to operate a device adapted to bring together the centre line of the strip and the centres of the tools. One form of such device is shown in Figure 4, and consists of a hydraulic or pneumatic or steam cylinder 22, of which the piston rod 23 carries a roller 24 adapted to press against the edge of the strip. A similar cylinder, located at the other side of the strip 4 is adapted to press against the other edge. Pressure fiuid is supplied to the valve box 20 by the pipe 25, and is transmitted by the pipes 26 to the two cylinders 22, the supply being transmitted to the cylinder shown when the arm I9 is turned to the left and to the other cylinder when the arm is turned to the right. The cylinders 22 may be located close to the device of Figure 3, or at a point of the strip nearer to the leer. The pressure of the fluid supplied to the cylinders is adjusted to a value which prevents the pressure of the roller 24 on the edge of the strip from reaching a pressure sufficient to break the strip. By this meansQwhen the centre line of the strip moves laterally from its normal central position in the apparatus, pressure is applied to its edge tending to force it back to its normal central position.

In our co-pending application for Letters Patent S. N. 193,908 filed March 4th 1938, a device is described whereby the tools of the grinding and polishing apparatus may be moved transversely of the strip. This device is shown in Figure 8 in which the grinding tools I run in bearing. blocks 44 adapted to slide transversely on cross girders 45. The construction of the apparatus is described in detail in the said application for Letters Patent. The bearing blocks 44 are moved transversely by means of screwthreaded rods '46 engaging nuts on the bearing blocks, the rods 46 being connected together by gear-wheels 41 and 48 and shafts 49, and connected to a motor 50 by worm gear 5| and bevel gear 52. The device shown in Figure 3 is shown diagrammatically in Figure 8, with the wheel |2 on the arm I3, engaging the groove in the strip 4 behind the upper grinding tool I. The arm I3 i pivoted at M to the rod l5, which is pivoted to a bracket IE on the frame. The rod 5 is connected at 53 by the rod 54 to the relay switch 55 of a reversing switch in the circuit of the motor 50, the switch 55 being fixed to the lower hand contact 51 to stop the motor.

bearing block 44. The switch '55 is shown diagrammatically in Figure 9, the arm 54 being connected to the contact arm 56 of the switch, adapted to contact with one or other of the contacts 51 and thus to operate the motor reversing switch to rotate the motor in one or the other direction. ,It then the groove H in the strip 4 moves to the right (in Figure 8) the arm l3 and rods l5 and 54 move to the right, to cause the contact arm to make contact with the right hand contact 51. Thereby the motor 50 moves the bearing blocks 44 of the grinding tools I to the right until the switch 55 has moved to bring the contact arm 56 out of contact with the right The tools are then in their original position relatively to the groove II, that is to say, relatively to the centre line of the strip. Instead of marking the strip with a V-groove as indicator of the position of its centre line, two bands may be laid on the strip of opaque paint or the like. These bands may be laid on at any point in the'leer at which the strip still retains its central position, so that the band serves as indicator of the centre line of the strip. Figures 5 shows a device whereby a lateral movement of the strip causes a light-sensitive cell to operate a device for'bringing together the centre line of the strip and the centres of the tools. The opaque band laid on the strip 4 near one edge is shown at 21 and a light-sensitive cell 28 is placed above the strip and a light source 29 below it, the band 21 shielding the cell 28 from the light source 29 when the strip is central. The cell' is connected to an amplifier or primary relay 30, which is adapted to operate a relay 3|, adapted to close the circuit of a solenoid 32 of which the core 33 is adapted to operate the arm I9 of the valve box 20. If the strip moves to the right, so that the band 21 no longer shields the cell from the light, the arm I9 is operated to cause the cylinder 22 on the other side of the strip to press the strip to the left. A similar band is laid on the strip near the other edge, and a similar device consisting of cell, light source, relays, solenoid and valve box serves to cause the strip to be pressed to the right, if it moved to the left. The V-groove has an advantage over the band 21, in that it serves as an indicator of the centre line of the strip at any point in the grinding and polishing apparatus, whereas the band is removed by the first grinding tool and can serve as indicator only up to this tool.

Figure 6 shows diagrammatically .a device for indicating the position of the centre line of the strip at any point, without marking the strip near its point of formation. Two rollers 34, carried on arms 35, turning on fixed pivots 36, are pressed against the two edges of the strip 4 by springs 31. The arms 35 are connected by links 38 to the two ends 39 of a lever arm pivoted at 40 to an arm 4| which is pivoted at 42 to a fixed support and engages at 43 the arm I!) of the valve .box 20. By this means, any point on the arm 4| moves proportionately to the movement of the centre line of the strip, and any variation in the width of the strip without movement of the centre line causes the lever 39, 39 to turn about its pivot 40 wihtout turning the arm 4|. The devices shown in Figures 5 and 6 may be employed to operate devices other than the valve box 20, as was explained in connection with. the device of Figure 3.

Having described our invention, we declare that what we claim and desire to secure by Letters Patent is:

1. In a glass grinding apparatus including a plurality of grinding tools arranged to operate simultaneously on both surfaces of a continuous strip of glass passing through the apparatus, the combination of means for shifting the strip and grinding tools laterally, one relatively to the other to maintain the strip and grinding tools in centralized relation during the grinding period, and automatic means for controlling the operation of said shifting means to correct .for any deviation from said centralized relation.

2. In a glass grinding apparatus including a plurality of grinding tools arranged to operate simultaneously on both surfaces of a continuous strip of glass passing through the apparatus, the means for controlling the operation of said shiftcombination of means for shifting the strip lating means to correct for any deviation from said erally relatively to the grinding tools to maintain centralized relation. the strip and grinding tools in centralized rela- FREDERIC BARNES WALDRON.

5 tion during the grinding period, and automatic FRANK EDWIN SLOCOMBE. 

